Sigma 170-500mm or Tonica 80-400mm

Hi,
I am thinking of buying new lenses to photograph wildlife.I have Canon 450D /lenses mount EF/,and I have Canon lenses 70-300mmIS USM.I like this lenses very much ,but I need something for bigger distance./sorry my English is not the best/.Original Canon lenses are too expensive so I think about Sigma 170-500mm or Tonica 80-400mm.
Does anybody use these lenses? What is your opinion ,which one is better???

These lenses are OK but not great - neither have any kind of vibration reduction. The Tokina gives you 400mm in a small package - I bought a used one that I used to use on hikes when I didn't want to carry a larger lens. Expect to use a monopod - or better yet, a tripod. The 170-500 needs a tripod for clear shots at 500.

In my opinion, it's worth having some kind of vibration reduction when shooting wildlife - at least in the wild. You may have unexpected opportunities and want to shoot quickly hand held or with a monopod. Vibration reduction definitely makes a difference. I hae a 200-400 which isa great lens but very expensive and a bit too lare and heavy for many situations. Looking for a smaller long lens WITH vibration reduction, I got the Sigma 150-500.

I used it extensively for wildlife shots over the past month on vacation. It IS a bit slow (f5-6.3) and you'll want good light but it worked well for me. I was shooting next to someone with a 170-500 on a tripod. She tried my camera/lens and was astounded that she could hand-hold and get good shots.

The 120-400 is faster and a bit smaller - as well as cheaper - and might be a good option for you. It'll be about 25% more than the lenses you're considering but it's worth the cost.

Unfortunately the Nikon 80-400 is NOT AF-S and slow focusing - and expensive. Many of the other 400 or 500 zoom lenses from other manufacturers are older designs and not as good optically - few have any kind of Vibration Reduction. The old Sigma 50-500 does NOT have OS (Sigma's VR) though their 80-400 did.

I bought the 150-500 as a smaller and lighter alternative that I could hand hold or use on a monopod - something I could take on hikes. It's not as good as the 200-400 but then it is 1/6 the price - I think I got my money's worth.

Finally somebody helps!!!!1
Thank you very much.I was thinking of Sigma 150-500mm but I am afraid it can not fit to my camera.When I checked it,it looks that they are for Canon Af-mount lenses.My camera has EF ,EF-S mount .Photography is my new hobby ,so I have to learn a lot ,and every advise is valuable for me.For sure I would prefer something not too heavy ,so it is easier to travel with it.,but the most important is quality.
Thanks a lot for your advice

I use the 150-500 on an XTi, so there is no worry about it not working on your camera. It is a bit heavy, but on a sunny day, it can be handheld. The image stabilization (OS on Sigma) is very useful; and I usually use this lens with a monopod. Unfortunately it is on the expensive side, but if you want a long lens, you will be paying quite a bit. I have been satisfied with the quality, sharp pictures, good OS. Before you jump into this kind of purchase, make sure you read more, learn some more things whatever it may be, and be sure about this purchase.

Yes ,I have to read a lot.What I am going to do I will choose 3 or 4 lenses and will also ask the shop assistent if they will fit to my camera.I know that I will have to pay more for 500mm and better quality.I heard that the best would be for example Canon 100-400mm ,but the price is quite high.
I was surprised that I couldn`t find many reviews odf Sigma lenses.
Today I met somebody who used Sigma 50-500mm,they seem to be ok ,although quite heavy.What you think about them?

Your rebel will take any of the new Sigma lenses for Canon. I shoot with the Sigma 50-500 myself. I am not totally sold on IS or VR or whatever. Its nice, but not a must have. Tripods are better for these long lenses and moving wildlife anyways. Technology is such, that acceptable images can be taken with todays "super zooms". Many nay-sayers will disagree, but times are changing. I find my images from the 50-500 very acceptable. It is a heavy lens though.